Shin Gou wrote:

Could anyone give me a suggestion of good airplane design consultant
with a reasonable service charge for light/sport airplane conceptual
design? A professional design agency would be great, but I believe a
graduate student in aeronautical engineering should be able to help me
out.

I am not an engineer and only have private pilot's paper test level
aeronautical knowledge(don't sneer at me. I passed the test in the
first try!), but I am now just fascinated with the idea of designing
and building and yes, flying my own airplane! I am brainstorming a
twin 3/4 seat camper design using two Rotax 912S or Jabiru 3300 with
reliability(twin), simplicity(tube and fabric?), ruggedness(tube and
fabric and STOL), comfortability(large cabin for two sleeping)and low
cost in mind. I know I probably wouldn't have enough money and time to
build it anytime soon, but I just can't wait for proving the design
and seeing the airplane layed out on the blue print!

So now my goal is to get to the first stage: the conceptual and
preliminary design. Then I will save money for structure design and
stability analysis etc. Finally I hope I can have the construction
plan and then from there I can build the plane piece by piece over
time.

I know nowadays such light airplane design could be totally done on a
computer and there're some dirty cheap entry-level airplane design CAD
softwares I can play with, but these softwares do need human input
with sufficient aeronautical knowledge even though they look like a
dummy's software for those enginners who operate 150K REAL airplane
design CAD systems. So is there anyone good at any of those softwares
like AirplanePDQ or even X-Plane PlaneMaker who would like to help me?

Thank you in advance.

Shin Gou


Any CAD and any spreadsheet.

Those are the modern tools of creation, and as great an 'equalizer'
as the Colt's 45 was in the Olde West.

HOW you use them, as you pointed out, is the critical question.

While the programs you asked about can produce results, it's left up
to the operator to determine if those results are valid.
"Therein lies the rub", as the Bard put it.

There are a lot of web sites that deal with aerodynamics and design.
That would be one possible way to get up to speed.

Another, more traditional way, is to acquire and study - books.
Maybe the guys here on the group will chip in with suggestions.

At first "Aerodynamics for Naval Aviators" looked mighty intimidating.
That was most of a lifetime ago, and now it seems almost superficial.

But one must start somewhere...

Below is the source listing for a simple (minded?) little program
that I often use to study the relationship between wing design
options.

It doesn't produce pretty pictures or anything like that.
But it _does_ let one play with the major parameters and see how
they interact.

The idea is to pick one parameter to SOLVE for, based on given
values for the rest of them.

Coefficient of lift, wing Surface, Airspeed, and total Lift are
the changeable values. It assumes a sea level standard day.

I wrote it in the BASIC language and should run under just about
any interpreter or compiler with little if any modifications required.

This version is much better structured, and the line numbers have been
discarded in favor of Labels so that even the most rabid C-Hag can
follow.

All I ask in return is that if you take it and extend it into
something more useful, send me a copy? (source code, dude!)


Best wishes,

Richard Lamb
http://home.earthlink.net/~n6228l/


============= cut here =================

FF = 0
TT = NOT FF
doRun = TT
KK$ = "LVSCQ?"
'initial values:
L = 555
W = L
A = 55
V = A * 1.4666
CL = 1.2
S = 125

CLS
PRINT "Finite Wing Theory"; " print"
WHILE doRun = TT
PRINT "[.L.V.S.C.Q.] for Lift Velocity Surface Clift Quit "; Z$
Z$ = ""

WHILE Z$ = ""
Z$ = UCASE$(INKEY$):
IF Z$ = CHR$(13) THEN Z$ = ""
IF Z$ = CHR$(27) THEN Z$ = "Q"
IF INSTR(KK$, Z$) = 0 THEN Z$ = ""
WEND

PRINT
SELECT CASE UCASE$(Z$)
CASE "L"
PRINT " Calculate LIFT.............."
GOSUB doLift
CASE "V"
PRINT " Calculate Velocity.........."
GOSUB doVel
CASE "S"
PRINT " Calculate Wing Area........."
GOSUB doSurf
CASE "C"
PRINT " Calculate Coef. of Lift....."
GOSUB doCL
CASE "?"
'GOSUB doDump
PRINT
PRINT " Variable dump:---------------------------"
PRINT " Lift / Weight "; L; " lbs"
PRINT " Airspeed "; A; " mph = "; V; " fps"
PRINT " Coefec of Lift "; CL
PRINT " Wing Area "; S; " sq ft"
PRINT " -----------------------------------------"
CASE "Q"
doRun = FF
END SELECT

PRINT : PRINT
WEND
END


doLift:
GOSUB GetSurf
GOSUB GetVel
GOSUB GetCL
L = .001188 * CL * V * V * S
PRINT " Lift = "; L
RETURN

doVel:
GOSUB GetSurf
GOSUB GetCL
GOSUB GetWgt
V = SQR(L / (.001188 * CL * S))
A = V * .681
PRINT " Velocity = ";
PRINT USING "#,###.#"; A;
PRINT " MPH = ";
PRINT USING "#,###.#"; V;
PRINT " FPS"
RETURN

doSurf:
GOSUB GetCL
GOSUB GetWgt
GOSUB GetVel
S = L / (.001188 * CL * V * V)
PRINT " Surface = "; S
RETURN

doCL:
GOSUB GetWgt
GOSUB GetVel
GOSUB GetSurf
CL = L / (.001188 * S * V * V)
PRINT " Coeff. Lift = "; CL
RETURN

GetSurf:
PRINT " Wing Area (sq ft) ["; S; "]";
INPUT ""; X
IF X 0 THEN S = X
RETURN

GetVel:
PRINT " Airspeed (mph) ["; A; "]";
INPUT ""; X
IF X 0 THEN
A = X
V = X * 1.467
END IF
RETURN

GetCL:
PRINT " Coeff. Lift (#.##) ["; CL; "]";
INPUT ""; X
IF X 0 THEN CL = X
RETURN

GetWgt:
PRINT " Gross Weight (lbs) ["; L; "}";
INPUT ""; X
IF X 0 THEN
W = X ' steady state W = L
L = X
END IF
RETURN